British patent GB-1 046 518 or German utility model DE 29508151 disclose a dispenser head for a receptacle having a flexible wall, the head comprising a rigid endpiece surmounted by a closure membrane made of rubber or of elastomer and provided with a slot made by cutting through the membrane and having edges that touch each other at rest.
When the user exerts pressure on the wall of the receptacle, the edges of the slot move apart under thrust from the fluid.
That kind of dispenser head does not make it easy to measure out the fluid.
To extract fluids, the user must press hard against the wall of the receptacle and, when the slot opens, the fluid is dispensed suddenly.
The user can then be surprised and stop pressing too late on the receptacle, thereby causing too much fluid to be dispensed.
In its French patent application No. FR-A-2 745 552, the Applicant company has described a dispenser head including a flow reducer member made of an elastically deformable plastics material, provided with a slot having non-touching edges, which slot is therefore never completely closed and makes it easier to measure out the fluid while nevertheless preventing it from leaking out of the receptacle when at rest.